Light and electron microscopic studies of lectin binding on the glycocalyx of rat pancreatic cells. I. Normal tissue and isolated cells.

Lectin binding of the glycocalyx of pancreatic tissue sections as well as of isolated pancreatic acini and acinar cells was studied of healthy wistar rats by light and electron microscopy. For light microscopy, we used FITC (WGA, RCAI, LCA) or peroxidase marked (WGA, RCAI, PNA, PHA, LCA, UEAI, LPA) as well as unmarked lectins (Con A, VAA I). Gold marked lectins were used for electron microscopy (WGA, RCAI, LCA, HPA, PNA, VAAI-B). Intact acinar cells in pancreatic tissue sections and isolated acini showed a strong binding of WGA, RACI, and HPA on the apical cell surface, whereas VAAI, UEAI, LCA, and Con A reacted strongly with the basolateral glycocalyx, but not with the apical surface. The 2 main domains of the glycocalyx of pancreatic cells showed their specific lectin binding so long as the junctional complexes between the cells are intact. The polarity of the cell surface of pancreatic acinar cells is discussed in regard to the possible function of the 2 domains.     

A study of lectin bindings to the fetal membranes.

Human tissues contain carbohydrates for a main component, functioning as a source and reservoir of energy, connective and supporting element, recognition site and related tasks. Our main interest is to reveal the synthesis and distribution of carbohydrate elements in human fetal membranes. The aim of our work was to clarify, which kinds of elements containing carbohydrates, existed in the fetal membranes. Therefore we applied a lectin-binding study using the following FITC labelled lectins: ConA, WGA, PNA, LCA, RCA. This lead to the result, that ConA, LCA, WGA and RCA produced a positive reaction in the amnion epithelium, which was negative when using PNA. The basement membrane I showed an intense fluorescence when we used ConA, LCA and WGA, using RCA it was weaker and using PNA fluorescence was nearly missing. The examination of the amniotic fibroblast and intercellular substance showed a positive reaction with all lectins, but the intercellular substance lead to weaker fluorescence. The chorionic fibroblasts, intercellular substance and basement membrane II produced fluorescence using ConA, LCA, WGA and PNA, but no reaction could be examined, when using RCA. The trophoblastic cells did not react with LCA and RCA. The intercellular substance reacted positively with all lectins.     

外阴营养不良、外阴鳞状上皮细胞癌凝集素标记免疫组化分析

目的：探讨外阴营养不良增生型,硬化苔藓型表皮细胞和外阴鳞状上皮细胞癌等细胞膜结构与凝集素受体结合表达特征及它们三者之间的关系。方法：对慢性外阴营养不良表皮增生型,苔藓硬化型及外阴鳞状上皮细胞癌3种状态下的细胞进行了8种凝集素免疫组织化学标记,分析,比较。结果：外阴营养不良增生型表皮各层细胞细胞膜与刀豆凝集素（ConA),扁豆凝集素（LCA）,花生凝集素（PNA）,蓖麻凝集素（RCA－1）和大豆凝集素（SBA）结合强度弱,其表皮细胞细胞核膜与ConA,PNA和麦胚凝集素（WGA）有中等强度结合,外阴营养不良硬化苔藓型表皮各层细胞细胞膜与ConA,RCA-1 SBA和WGA结合强度弱,而与LCA不结合,其12例中的8例与荆豆凝集素（UEA－1）发生较弱的结合,外阴鳞状上皮细胞癌癌细胞与8种凝集素均结合,其12例中的7例其癌细胞膜与双花扁豆凝集素（DBA）弱结合,癌细胞膜与UEA－1强结合,但癌巢中央细胞团不与UEA－1结合,癌细胞细胞核膜与ConA,LCA,RCA-1呈强结合。结论：凝集素标记免疫组织化学染色可作为诊断,鉴别诊断外阴营养不良增生,硬化苔藓型和外阴鳞状上皮细胞癌新的指标,具有恶变潜能的增生型外阴营养不良与外阴鳞状上皮细胞癌,两者细胞核膜凝集素标记有相似之处,提示在外阴组织的癌变过程中,细胞核膜凝集素标记的异常表达是一个早期标识,糖基和糖蛋白代谢的异常可能是细胞发生癌变最早期的表现之一。     

Changes in glycoconjugate expression during early chick embryo development: A lectin-binding study

A selection of lectins was used to investigate developmentally regulated changes in the distribution of cell surface oligosaccharides during the gastrulation and neurulation stages of early chick embryo development. Lectins from three specificity classes were used: glucose/mannose specificity (concanavalin A [Con A], Lens culinaris agglutinin [LCA], Pisum sativum agglutinin [PSA]); N-acetylglucosamine specificity (Lycopersicon esculentum agglutinin [LEA], wheat germ agglutinin [WGA], succinylated WGA [sWGA]); N-acetylgalactosamine/galactose specificity (Dolichos biflorus agglutinin [DBA], soybean agglutinin [SBA], Sophora japonica agglutinin [SJA], Bandeiraea (Griffonia) simplicifolia lectin I [BSL I], peanut agglutinin [PNA], Artocarpus integrifolia lectin [Jacalin], Ricinus communis agglutinin-1 [RCA-1], Erythrina cristagalli lectin [ECL]). At gastrulation stages, patterns of lectin binding could be distinguished in the epiblast, mesoderm, and endoderm cell layers. The primitive streak failed to bind any of the lectins, but LEA and WGA bound to the epiblast in regions lateral to the streak, indicating the loss of some glucosamine residues medially in preparation for the ingression movements of gastrulation. Several lectins showed marked binding to the mesoderm cells after their passage through the primitive streak; these were LCA, PSA, WGA, sWGA, BSL, and most particularly PNA. Therefore, the epithelial-mesenchymal transformation from epiblast to mesoderm at the primitive streak is accompanied by cell surface oligosaccharide changes in the epiblast and mesoderm that involve all classes of lectins including the PNA-binding sequence Galβ1-3GalNAc. Ultrastructurally, PNA was shown to bind extracellularly to matrix fibrils. Jacalin, having the same sugar specificity as PNA, but binding to serine/threonine linked chains rather than asparagine linked chains showed no binding to the mesoderm. The endoderm layer most clearly bound WGA and BSL. At neurulation stages, medio-lateral domains in the ectoderm could again be demonstrated. Neural plate cells bound only PNA, although the hinge point of the neural plate, the future floor plate, failed to bind PNA unless pre-treated with neuraminidase to remove sialic acid residues. Caudally, where the primitive streak persisted, all mesoderm cells reacted very strongly with PNA, but rostrally this binding became more restricted to the mesodermal regions immediately adjacent to the streak. This mesodermal PNA-binding was abolished by hyaluronidase pre-treatment, suggesting extracellular matrix association, whereas the neural plate binding was unaffected by this treatment, suggesting a more intimate developmentally regulated association with the cell surface of early neural cells. Neuraminidase treatment and sWGA-binding indicated patterns of sialylation on cells of several tissues at the later stages of development. These sialic acid residues had the effect of masking both PNA and ECL reactivity. The latter, specific for sequences of the poly-N-lactosamine series, (Galβ1-4GlcNAc)_n, bound to mesoderm only after removal of sialic acids. Basement membranes bound lectins of glucose/mannose and galactose specificities at both stages, and RCA-binding was localized ultrastructurally to the fibronectin-rich interstitial bodies of the lamina densa.     

Characterisation of glycoconjugate sugar residues in the vomeronasal organ of the armadillo Chaetophractus villosus (Mammalia, xenarthra)

Conventional carbohydrate histochemistry and the binding patterns of 21 lectins were analysed to characterise the glycoconjugate content in the components of the vomeronasal organ of the armadillo Chaetophractus villosus . The mucomicrovillous complex of the sensory epithelium bound most of the lectins studied. No reaction was observed with Con A, PSA, S-Con A and SBA, and the sustentacular cells were stained with UEA-I, DSL, LEL, STL and Con A. The vomeronasal receptor neurons were labelled with S-WGA, WGA, PNA, UEA-I, STL, Con A, S-Con A, ECL and RCA₁₂₀. The basal cell layer reacted with S-WGA, WGA, LCA, UEA-I, DSL, LEL, STL, Con A, JAC and VVA. The nonsensory epithelium exhibited a differential staining in relation to the different components. The mucociliary complex stained with ECL, DBA, JAC, RCA₁₂₀, STL, LCA, PHA-E, PHA-L, LEL, BSL-I and VVA. However, SJA and UEA-I stained the mucus complex lining a subpopulation of columnar cells. The cytoplasm and cell membranes of columnar cells was labelled with DBA, DSL and LCA. The apical region of these cells exhibited moderate reactivity with LEL and SJA. None of the lectins bound specifically to secretory granules of the nonsecretory cells. Basal cells of the nonsensory epithelium were labelled with DSL, LEL, LCA, BSL-I and STL. The vomeronasal glands showed a positive reaction with WGA, DSL, LEL, LCA, DBA, PNA, RCA₁₂₀ and SBA. Subpopulations of acinar cells were observed with ECL, S-WGA, Con A, S-Con A and DBA. PNA and RCA₁₂₀ stained the cells lining the glandular ducts. In comparison with previous results obtained in the olfactory mucosa of the same group of armadillos, the carbohydrate composition of the vomeronasal organ sensory epithelium differed from the olfactory sensory epithelium. This is probably related to the different nature of molecules involved in the perireceptor processes.     

Distribution and nature of membrane receptors for different plant lectins in the coelomocyte subpopulations of the Annelida Nereis diversicolor

Studies on membrane receptors have been performed on the Nereis coelomocytes using various lectins. In the agglutination assay, only LCA and WGA appeared nonreactive. Fluorescent lectins showed the poor reactivity of the eleocytes and the diversity of the receptors according to the granulocyte types. Types I-granulocytes reacted only with Con A. Type II-granulocyte membrane contained mannose and galactose receptors (reactivity with Con A, PNA and SBA). The type III-granulocyte membrane revealed the presence of mannose and fucose receptors (UEA, AAA). Electron microscope investigations with HRP-DAB or mannosyl labelled Con A, RCAI and LTA have confirmed the distribution of the membrane receptors.     

Histochemical mapping of glycoconjugates in the testis of the one humped camel (Camelus dromedarius) during rutting and non-rutting seasons

In the present study, the distribution of various sugar residues in the testicular cells of sexually mature camels during rutting and non-rutting seasons was examined employing 10 fluorescein isothiocyanate- (FITC) conjugated lectins. Lectin labeling was restricted to the germ cell lines and interstitial Leydig cells, while the Sertoli cells remained completely unlabeled. Our results revealed the presence of mannose (labeled by lectins PSA, LCA), galactose (labeled by PNA), GalNAc (labeled by HPA), and GlcNAc (labeled by WGA) residues in the camel spermatogonia. However, spermatocytes were only labeled with mannose (PSA, LCA) and GlcNAc (WGA) binding lectins. Binding sites for PSA, LCA and WGA in spermatogonia and spermatocytes were only evident during the rutting season. Although spermatids were exclusively labeled with PNA in the non-rutting seasons, other lectins (PSA, GSA-I, WGA) additionally bound to camel spermatids during the rutting period. Leydig cells and basal lamina of the seminiferous tubules of camel testis were consistently labeled with the mannose- (PSA, LCA) and GlcNAc- (WGA) binding lectins in both seasons, while DBA-labeling was seen in the Leydig cells during rutting period only. In conclusion, the findings of the present study clearly indicate that the camel testis contains a wide range of glycoconjugates (bearing mannosyl, galactosyl and glucosyl residues), and they lack fucosyl residues, both in the active sexual period and in the non-breeding season. The topographical distribution of the sugar moieties in the camel testis may indicate that specific carbohydrate structures are required for spermatogenesis during periods of sexual activity.     

Expression of glycoconjugates on normally developing and immunologically impairedHymenolepis diminuta

The carbohydrates on the surface ofHymenolepis diminuta were analyzed with gold-labelled lectins, and it was found that the surface coat of the anterior body differs from that of the strobila in its lectin-binding properties. Binding sites for lectins fromAbrus precatorius (APA),Arachis hypogaea (PNA),Glycine max (SBA) and for wheat germ agglutinin (WGA) and succinylated WGA were located on the scolex and strobilation zone. Lectin-gold particles attached mainly to the electron-dense spines. The surface coat may therefore expose sugar residues of theN-acetylglucosamine and galactose types. In contrast, the strobila had few binding sites for the above-mentioned lectins but bound concanavalin A (ConA). Lectins fromDolichos biflorus (DBA) andUlex europaeus (UEA-I) were not bound toH. diminuta. In juvenile worms from rats, the extension of the WGA- and SBA-positive region of the strobilation zone increased in length with the development of the worms. Lectin binding in juveniles from mice was similar when the mice had been immunosuppressed with cortisone. After the onset of the immune defense againstH. diminuta in nontreated mice, a moderate expression of lectin-binding substance also occurred on the strobila. Destrobilated worms were entirely covered with theN-acetylglucosamine- and galactose-containing glycoconjugates, and it is suggested that these worm remnants correspond to the lectin-binding part of normal, growing juveniles. The presence of the carbohydrates is discussed with respect to the relative resistance of the scolex-strobilation zone ofH. diminuta to immune rejection.     

<Emphasis Type="Italic">Fasciola hepatica</Emphasis> miracidia: Lectin binding and stimulation of <Emphasis Type="Italic">in vitro</Emphasis> miracidium-to-sporocyst transformation

The lectin binding properties of Fasciola hepatica miracidia were studied by a panel of fluorescein- and gold-conjugated lectins (ConA, LCA, WGA, LEA, SBA, HPA and UEA-I). The presence of mannose and/or glucose residues was demonstrated with ConA and LCA as weak diffuse fluorescence of the miracidial surface, which was more intense at the anterior part of the larva. The N-acetylglucosamine-binding lectins WGA and LEA reacted intensely with the whole miracidial surface. No labelling with N-acetylgalactosamine and/or galactose-specific (SBA and HPA) and fucose-specific UEA-I lectins was observed. The possibility that the specific recognition of the miracidial surface carbohydrates by lectins may initiate the process of transformation of the miracidia into sporocysts was examined in vitro in physiological saline for Galba truncatula. Incubation in the presence of ConA and WGA resulted in facilitation of the transformation process. Facilitation was absent in the presence of inhibitor sugars. Incubation in the presence of SBA or UEA-I had no effect. The results suggested a possible impact of carbohydrate-lectin interactions in transformation of miracidia of F. hepatica to sporocysts in vivo.     

Lectin binding sites on human sperm and spermatogenic cells

Testes of sexually mature men were studied histochemically with 20 fluorescein isothiocyanate-labeled lectins. Based on their pattern of reactivity with intratesticular spermatogenic cells, lectins were divided into five groups: 1) lectins reacting with all spermatogenic cells (Suc. ConA, WGA, LCA, PHA-E, PHA-L, STA, MPA, and RCA-II); 2) lectin reacting with spermatocytes, spermatids, and spermatozoa, but not with spermatogonia (RCA-I); 3) lectins reacting with spermatids and spermatozoa only (BPA, PNA, SBA, and VVA); 4) lectins reacting only with spermatozoa (HPA, GSA-I, UEA-II, and GSA-II); and 5) lectins with no distinct staining of spermatogenic cells (DBA, LBA, and UEA-I). All lectins from groups 1-4 were reactive with ejaculated spermatozoa. On the basis of the staining patterns of the head region of ejaculated spermatozoa, four lectin reactivity groups were defined: 1) lectins reacting with the plasma membrane of the whole head (BPA, WGA, LCA, STA, RCA-II, PHA-E, PHA-L, RCA-I, UEA-II, and GSA-II); 2) lectin reacting with the acrosomal cap and postacrosomal region of the plasma membrane (Suc. ConA); 3) lectin reacting with the acrosomal cap region of the plasma membrane (PNA); and 4) lectins reacting with the midregion of the sperm head in a bandlike manner (HPA, VVA, SBA, GSA-I, and MPA). These data provide a map of lectin binding sites on human testicular spermatogenic cells and ejaculated spermatozoa and show that the distribution of glycoconjugate domains of spermatogenic cell changes during differentiation and maturation.     

Changes in glycoconjugate expression during early chick embryo development: a lectin-binding study.

A selection of lectins was used to investigate developmentally regulated changes in the distribution of cell surface oligosaccharides during the gastrulation and neurulation stages of early chick embryo development. Lectins from three specificity classes were used: glucose/mannose specificity (concanavalin A [Con A], Lens culinaris agglutinin [LCA], Pisum sativum agglutinin [PSA]); N-acetylglucosamine specificity (Lycopersicon esculentum agglutinin [LEA], wheat germ agglutinin [WGA], succinylated WGA [sWGA]); N-acetylgalactosamine/galactose specificity (Dolichos biflorus agglutinin [DBA], soybean agglutinin [SBA], Sophora japonica agglutinin [SJA], Bandeiraea (Griffonia) simplicifolia lectin I [BSL I], peanut agglutinin [PNA], Artocarpus integrifolia lectin [Jacalin], Ricinus communis agglutinin-1 [RCA-1], Erythrina cristagalli lectin [ECL]). At gastrulation stages, patterns of lectin binding could be distinguished in the epiblast, mesoderm, and endoderm cell layers. The primitive streak failed to bind any of the lectins, but LEA and WGA bound to the epiblast in regions lateral to the streak, indicating the loss of some glucosamine residues medially in preparation for the ingression movements of gastrulation. Several lectins showed marked binding to the mesoderm cells after their passage through the primitive streak; these were LCA, PSA, WGA, sWGA, BSL, and most particularly PNA. Therefore, the epithelial-mesenchymal transformation from epiblast to mesoderm at the primitive streak is accompanied by cell surface oligosaccharide changes in the epiblast and mesoderm that involve all classes of lectins including the PNA-binding sequence Gal beta 1-3GalNAc. Ultrastructurally, PNA was shown to bind extracellularly to matrix fibrils. Jacalin, having the same sugar specificity as PNA, but binding to serine/threonine linked chains rather than asparagine linked chains showed no binding to the mesoderm.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lectin histochemistry for detection of the oligosaccharides in the testis of the chick embryo

The oligosaccharidic content, distribution and changes of the glycoconjugates in the testis of the chick embryo, from the 8th day of incubation to hatching, were studied using a battery of seven HRP-conjugated lectins (DBA, SBA, PNA, ConA, WGA, LTA, and UEA I). Our findings showed that ConA and WGA appeared to characterize the spermatogonia during their differentiation, maturation, migration and meiosis. In the Sertoli cells, a change of localization of staining with ConA and WGA was revealed during the differentiation and maturation of these cells. The basal membrane was characterized by the reactivity with ConA and WGA from the early stages of incubation. ConA, WGA and PNA reacted with the endothelial cells of the testis for the whole period of incubation considered. Moreover, the interstitial cells, since their appearance, showed reactivity with ConA, WGA and PNA at the plasma membrane and the cytoplasm.     

Binding studies of gold labelled lectins on carbohydrate compounds of the flask cells in claw-frog kidney.

The carbohydrate compounds of the mucus of flask cells in the kidney of claw-frogs (Xenopus laevis) were studied by gold marked lectins (WGA, RCA, L, LCA, HPA, PNA). We used a post-embedding technique. Seminthin or ultrathin sections of Lowieryl K H M-embedded kidney tissue were incubated. For light microscopy, a gold-silver technique was used. The mucus of the flask cells reacted strongly with WGA, RCA L and HPA, whereas LCA and PNA showed no binding. The Golgi apparatus and small cytoplasmatic vesicles reacted also positively with WGA, RCA L and HPA. The autoradiographically detected secretion routes of the glycosaminoglycan-rich secretion of flask cells are also demonstrable by lectins.     

Lectin-binding patterns of small lymphocytes in bone marrow,thymus and spleen: demonstration of lymphocyte subsets by quantitative radioautography

Cells from mouse bone marrow, thymus and spleen were exposed to ¹²⁵I-labeled concanavalin A (Con A), Lens culinaris lectin (LCL), soybean agglutinin (SBA), Helix pomatia agglutinin (HPA), phytohemagglutinin-P (PHA-P), peanut agglutinin (PNA), or wheat germ agglutinin (WGA) in a range of concentrations and examined radioautographically. Small lymphocytes in the three organs differed in the minimal concentration of each lectin which gave detectable surface labeling, while at optimal lectin concentrations, their labeling intensity profiles differed markedly. Inhibition by sugars demonstrated the labeling specificity. Major populations of bone marrow small lymphocytes bound WGA strongly, while Con A, SBA, HPA, PHA-P and LCL were bound only weakly, and PNA binding was lacking. Most thymus cells bound Con A, SBA, HPA, PHA-P and PNA strongly, WGA and LCL weakly. Subsets of bone marrow and thymus small lymphocytes differed from the major populations in their lectin-binding intensities. Spleen small lymphocytes were heterogeneous in the binding of each lectin. However, a major population bound LCL exceptionally strongly, while few cells bound PNA. Using a panel of lectins under standardized conditions, these studies show distinctive lectin-binding patterns for small lymphocytes in the bone marrow, thymus and spleen, respectively. Major and minor cell populations are distinguishable in each organ, providing an approach to discriminating lymphocyte lineages, subtypes and differentiation stages.     

Wheat germ agglutinin-binding protein changes in highly malignant Friend leukemia cells metastasizing to the liver

We have used binding of radioactive lectins (i.e. Concanavalin A (ConA), Wheat Germ Agglutinin (WGA) andRicinus communis agglutinin I (RCA_I)) to membrane glycoproteins separated in SDS gel electrophoresis, to detect specific carbohydrate changes in plasma membrane proteins ofin vivo passaged Friend erythroleukemia cells (FLC). These cells are highly metastatic to the liver, whereas the originalin vitro passaged tumor cells do not metastasize. Marked qualitative differences in the high molecular weight region of the gels (100–200 kD) were observed between the WGA binding glycoproteins of metastaticin vivo passaged FLC and nonmetastaticin vitro passaged FLC. Furthermore, the binding of WGA to plasma membrane proteins ofin vivo passaged FLC was much greater than the binding of WGA to plasma membrane proteins ofin vitro passaged FLC. Lectin binding experiments after sialic acid removal byin situ mild acid hydrolysis of FLC glycoproteins indicated that an increased sialylation of the 120 and 145 kD glycoproteins was responsible for the increased WGA reactivity ofin vivo passaged FLC plasma membranes. Besides the increased sialylation, other changes in glycosylation of the 100–200 kD glycoproteins ofin vivo passaged FLC were observed: (1) qualitative differences between the WGA binding patterns of the two cell types were restored after treatment of the gels with mild acid and subsequent Smith degradation; (2) after chemical removal of sialic acid residues from the gels, qualitative differences in the RCA binding patterns to the glycoproteins of the two cell types were apparent.     

Identification and localisation of glycoconjugates in the olfactory mucosa of the armadillo Chaetophractus villosus

Conventional histochemistry and the binding patterns of 22 biotinylated lectins were examined for characterisation of glycoconjugates in the components of the olfactory mucosa of the armadillo Chaetophractus villosus . The mucous lining the olfactory epithelium showed binding sites for DSL, WGA, STL, LEL, PHA-E and JAC. Only the basilar processes of the supporting cells stained for Con-A and S-Con A. The olfactory receptor neurons stained with LEL, LCA, Con A, S-Con A, JAC and PNA. The layer of basal cells did not react with any of the lectins studied. Bowman's glands in the lamina propria showed subpopulations of acinar cells reacting with SBA, S-WGA, WGA, STL, Con A, PSA, PNA, SJA, VVA, JAC and S-Con A, but in our optical studies with lectins we were unable to differentiate between mucous and serous cells in the way that is possible on electron microscopy. The ducts of Bowman's glands were labelled with S-WGA, STL, LEL, PHA-E, BSL-I and JAC. This histochemical study on the glycoconjugates of the olfactory mucosa in the order Xenarthra provides a basis for further experimental investigations.     

Glycoconjugate expression in the chick embryonic chorioallantoic membrane: Comparisons of the chorionic ectoderm and allantoic endoderm

Background: The chorioallantoic membrne (CAM) of the chick embryo expands during embryogenesis to meet the increased oxygen demands during growth and differentiation. Temporal and spatial glycosylation patterns of CAM ectodermal and endodermal proteins likely contribute to differentiation of the functional attributes of the CAM. Methods: Using lectins for light and electron microscopic observations, we studied the patterns of glycoconjugate expression on the ectoderm and endoderm of the chorioallantoic membrane (CAM) of the chick at days 4.5, 5.0, 6.0, and 10 of morphogenesis. For light microscopy, samples of unfixed CAM were incubated with the following FITC lectins: Con A, DBA, GSA-I, GSA-II, PNA, SBA, UEA-I, and WGA. Results: All lectins, except GSA-I and -II, gave positive results. The positive lectins, labeled with HRP, served to ultrastructurally localize PNA, SBA, and WGA, but not DBA binding to the luminal surface of the endoderm. UEA-I and Con A bound similarly except on day 10 when UEA-I no longer bound. On the ectodermal surface, only WGA bound at all times studied. PNA and SBA binding were present from days 5.0 to 6.0 but absent at days 4.5 and 10. DBA binding occurred through day 5.0 but was absent thereafter. UEA-I bound to the ectoderm at days 4.5, 5.0, and 10 but not days 5.5 and 6.0 Con A bound only on days 5.0 and 10. Conclusion: That the ultrastructurally similar ectoderm and endoderm of the CAM display functional differences conforms to the hypothesis that differential expression of glycoconjugate microdoains likely contributes to such functional specialization. © 1995 Wiley-Liss, Inc.     

Localization of glycoconjugates at the tegument of the tapeworms Hymenolepis nana and H. microstoma with gold labelled lectins

Gold labelled lectins were used for electron microscopic localization of carbohydrate components of the tegument surface of two tapeworm species, Hymenolepis nana and H. microstoma. WGA, succinylated WGA, SBA, APA, PNA and, to a lesser extent, Con A were preferentially bound to the spines of the microtrichs. UEA-I and DBA were not adsorbed. The results indicate that the surface coat of both species has exposed N-acetylglucosamine, galactose and perhaps glucose and/or mannose residues.The location of lectin-binding glycoconjugates within the tegument and parenchyma was found using the light microscope on sections of material embedded in Lowikryl K4M after lectin-gold labelling and silver enhancement of the gold grains. The tegument selectively adsorbs WGA and SBA and strongly; adsorbtion of PNA and Con A is less intense. Strong adsorbtion of DBA and PNA was confined to the basal lamina. The parenchyma adsorbed Con A, PNA and DBA, but little WGA and SBA.The results indicate that many glycoconjugates are present in the tegument. They have similar terminal sugar residues to those of the surface coat. The significance of these carbohydrates for hostparasite interactions is discussed.     

Lectin binding patterns in salivary glands treated with amylase

Lectin binding patterns of ConA (Glc, Man), PNA and SBA (Gal, GalNAc), RCA-I (Gal) DBA (GalNAc), WGA (GlcNAc), and UEA-I (Fuc) in the major salivary glands of mice, rats, hamsters, and guinea pigs were reported using paraffin sections subjected to alpha-amylase treatment at 1, 3, and 6 h digestions. Lectin staining following treatment with amylase was generally enhanced in acinar, duct, and GCT cells. However, increasingly different reactions were obtained depending upon the lectins used, the various salivary glands from different specimens treated, and the different properties of the serous, mucous, and sero-mucous cells in the histologic sections. The lectins that demonstrated rather markedly increased staining were ConA, PNA, SBA, WGA, and UEA-I, whereas RCA-I and DBA increased little in comparison, or actually decreased. It appears from these findings that complex carbohydrates within murine salivary glands contained large amount of glucose, mannose, galactose, and N-acetyl galactosamine residues. The basement membranes of glandular cells in salivary glands demonstrated markedly positive ConA staining following alpha-amylase digestion.